net/ipv6/netfilter/ip6t_rt.c

   1 /* Kernel module to match ROUTING parameters. */
   2
   3 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/ipv6.h>
  13 #include <linux/types.h>
  14 #include <net/checksum.h>
  15 #include <net/ipv6.h>
  16
  17 #include <asm/byteorder.h>
  18
  19 #include <linux/netfilter_ipv6/ip6_tables.h>
  20 #include <linux/netfilter_ipv6/ip6t_rt.h>
  21
  22 MODULE_LICENSE("GPL");
  23 MODULE_DESCRIPTION("IPv6 RT match");
  24 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  25
  26 #if 0
  27 #define DEBUGP printk
  28 #else
  29 #define DEBUGP(format, args...)
  30 #endif
  31
  32 /* Returns 1 if the id is matched by the range, 0 otherwise */
  33 static inline int
  34 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
  35 {
  36         int r = 0;
  37         DEBUGP("rt segsleft_match:%c 0x%x <= 0x%x <= 0x%x",
  38                invert ? '!' : ' ', min, id, max);
  39         r = (id >= min && id <= max) ^ invert;
  40         DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
  41         return r;
  42 }
  43
  44 static int
  45 match(const struct sk_buff *skb,
  46       const struct net_device *in,
  47       const struct net_device *out,
  48       const struct xt_match *match,
  49       const void *matchinfo,
  50       int offset,
  51       unsigned int protoff,
  52       int *hotdrop)
  53 {
  54         struct ipv6_rt_hdr _route, *rh;
  55         const struct ip6t_rt *rtinfo = matchinfo;
  56         unsigned int temp;
  57         unsigned int ptr;
  58         unsigned int hdrlen = 0;
  59         unsigned int ret = 0;
  60         struct in6_addr *ap, _addr;
  61
  62         if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL) < 0)
  63                 return 0;
  64
  65         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  66         if (rh == NULL) {
  67                 *hotdrop = 1;
  68                 return 0;
  69         }
  70
  71         hdrlen = ipv6_optlen(rh);
  72         if (skb->len - ptr < hdrlen) {
  73                 /* Pcket smaller than its length field */
  74                 return 0;
  75         }
  76
  77         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  78         DEBUGP("TYPE %04X ", rh->type);
  79         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  80
  81         DEBUGP("IPv6 RT segsleft %02X ",
  82                (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  83                                rh->segments_left,
  84                                !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
  85         DEBUGP("type %02X %02X %02X ",
  86                rtinfo->rt_type, rh->type,
  87                (!(rtinfo->flags & IP6T_RT_TYP) ||
  88                 ((rtinfo->rt_type == rh->type) ^
  89                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  90         DEBUGP("len %02X %04X %02X ",
  91                rtinfo->hdrlen, hdrlen,
  92                (!(rtinfo->flags & IP6T_RT_LEN) ||
  93                 ((rtinfo->hdrlen == hdrlen) ^
  94                  !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
  95         DEBUGP("res %02X %02X %02X ",
  96                (rtinfo->flags & IP6T_RT_RES),
  97                ((struct rt0_hdr *)rh)->reserved,
  98                !((rtinfo->flags & IP6T_RT_RES) &&
  99                  (((struct rt0_hdr *)rh)->reserved)));
 100
 101         ret = (rh != NULL)
 102               &&
 103               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 104                               rh->segments_left,
 105                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 106               &&
 107               (!(rtinfo->flags & IP6T_RT_LEN) ||
 108                ((rtinfo->hdrlen == hdrlen) ^
 109                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 110               &&
 111               (!(rtinfo->flags & IP6T_RT_TYP) ||
 112                ((rtinfo->rt_type == rh->type) ^
 113                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 114
 115         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 116                 u_int32_t *rp, _reserved;
 117                 rp = skb_header_pointer(skb,
 118                                         ptr + offsetof(struct rt0_hdr,
 119                                                        reserved),
 120                                         sizeof(_reserved),
 121                                         &_reserved);
 122
 123                 ret = (*rp == 0);
 124         }
 125
 126         DEBUGP("#%d ", rtinfo->addrnr);
 127         if (!(rtinfo->flags & IP6T_RT_FST)) {
 128                 return ret;
 129         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 130                 DEBUGP("Not strict ");
 131                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 132                         DEBUGP("There isn't enough space\n");
 133                         return 0;
 134                 } else {
 135                         unsigned int i = 0;
 136
 137                         DEBUGP("#%d ", rtinfo->addrnr);
 138                         for (temp = 0;
 139                              temp < (unsigned int)((hdrlen - 8) / 16);
 140                              temp++) {
 141                                 ap = skb_header_pointer(skb,
 142                                                         ptr
 143                                                         + sizeof(struct rt0_hdr)
 144                                                         + temp * sizeof(_addr),
 145                                                         sizeof(_addr),
 146                                                         &_addr);
 147
 148                                 BUG_ON(ap == NULL);
 149
 150                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 151                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 152                                         i++;
 153                                 }
 154                                 if (i == rtinfo->addrnr)
 155                                         break;
 156                         }
 157                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 158                         if (i == rtinfo->addrnr)
 159                                 return ret;
 160                         else
 161                                 return 0;
 162                 }
 163         } else {
 164                 DEBUGP("Strict ");
 165                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 166                         DEBUGP("There isn't enough space\n");
 167                         return 0;
 168                 } else {
 169                         DEBUGP("#%d ", rtinfo->addrnr);
 170                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 171                                 ap = skb_header_pointer(skb,
 172                                                         ptr
 173                                                         + sizeof(struct rt0_hdr)
 174                                                         + temp * sizeof(_addr),
 175                                                         sizeof(_addr),
 176                                                         &_addr);
 177                                 BUG_ON(ap == NULL);
 178
 179                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 180                                         break;
 181                         }
 182                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 183                         if ((temp == rtinfo->addrnr) &&
 184                             (temp == (unsigned int)((hdrlen - 8) / 16)))
 185                                 return ret;
 186                         else
 187                                 return 0;
 188                 }
 189         }
 190
 191         return 0;
 192 }
 193
 194 /* Called when user tries to insert an entry of this type. */
 195 static int
 196 checkentry(const char *tablename,
 197            const void *entry,
 198            const struct xt_match *match,
 199            void *matchinfo,
 200            unsigned int matchinfosize,
 201            unsigned int hook_mask)
 202 {
 203         const struct ip6t_rt *rtinfo = matchinfo;
 204
 205         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 206                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 207                 return 0;
 208         }
 209         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 210             (!(rtinfo->flags & IP6T_RT_TYP) ||
 211              (rtinfo->rt_type != 0) ||
 212              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 213                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 214                 return 0;
 215         }
 216
 217         return 1;
 218 }
 219
 220 static struct ip6t_match rt_match = {
 221         .name           = "rt",
 222         .match          = match,
 223         .matchsize      = sizeof(struct ip6t_rt),
 224         .checkentry     = checkentry,
 225         .me             = THIS_MODULE,
 226 };
 227
 228 static int __init ip6t_rt_init(void)
 229 {
 230         return ip6t_register_match(&rt_match);
 231 }
 232
 233 static void __exit ip6t_rt_fini(void)
 234 {
 235         ip6t_unregister_match(&rt_match);
 236 }
 237
 238 module_init(ip6t_rt_init);
 239 module_exit(ip6t_rt_fini);